.spinner {
        margin 100px auto;
        width 50px;
        height 50px;
        text-align center;
        font-size 10px;
    }
    
    .spinner > div 
        display inline-block;
        width 5px;
        height 100%;
        background-color rgb(43,128,226)
        margin-right 1;
        animation bytedance 1s infinite;
        for num in (2..5)
            &:nth-child({num})
                animation-delay (-0.9 + (num - 2) * 0.1)s
        
    
    @keyframes bytedance 
        0%,
        40%,
        100% 
            transform: scaleY(0.4);
        
        20% 
            transform: scaleY(1);
        